At PIT, the period of record is 1871-2021, with 1948-2021 being at the airport, so it’s literally divided almost in half.
The number of top 10 months that occurred prior to 1948 is as follows:
Jan-7.
Feb-8.
Mar-7.
Apr-7.
May-7.
Jun-10.
Jul-9.
Aug-7.
Sep-10.
Oct-7.
Nov-5.
Dec-7.
That’s 91 out of 120 record warm months in half of the period of record, and only one month with less than 7. That’s why I’m skeptical of PIT’s data.
Notably, I don’t think MDT has this issue.